Important safety issue blogged by "Eliassaj" yesterday!

[reefrat]

"Weird , Near death causing stuff in regulator !!!

by eliassaj View Profile View Forum Posts Private Message View Blog Entries View Articles Add as Contact , Yesterday at 12:23 AM (231 Views)

I regularly check my gear before diving , following a routine that has become a second nature .
During the end of year dive , @44.3 meters , and while ascending , I had no air flow into the regulator.
checked my knob , Dive computer , SPG , all perfectly fine , I had 132 Bars.
Luckily , was able to get some air from my buddy . when on land , I disassembled the Gear , and I will leave you with the pictures, the filter was completely blocked , to mention that the regulator was working on and off during the ascent .... did anyone experience anything like this before?
NB : never submerge It in water , always close the cap after a dive , never left it Open and never consumed any tank below 50 Bars."

I copied the above text from a Scubaboard blog yesterday and have taken the liberty of posting it here because I think it is an important safety issue that not enough people are aware of! I also PM'ed the blogger as soon as I saw it.
I hope that is not inappropriate or in breach of any forum/ board rules to do copy and post this info, please let me know if it is?

The blogger also shows some images of a first stage filter totally clogged with white powder. This is almost certainly aluminum residue from the bottom of the tank and the problem is most likely the result of tank valve not having a small tube (don't know the right name) that protrudes into the tank from the valve base. The purpose of the tube is to prevent residue in a tank from entering the valve and clogging up the first stage filter. The problem occurs if the diver assumes a head down attitude and the residue moves to the top of the tank.
I have personally picked up two rental tanks (different locations- years apart) and noticed a rattling sound inside when I moved them- this is the small tube and it has fallen off inside the tank. In both cases I brought it to the attention of the dive staff and in both cases they had no idea of the significance of situation.

This is one of the few conditions that can result in a sudden and complete failure of a first stage to deliver any gas and is extremely dangerous! Shaking a tank to see if it rattles should probably be a routine pre-dive check before any dive with rental tanks!

Anyone else encountered this before!

 

[Matt S.]

This hasn't happened to me, but it did happen to someone in my dive club. He went upside down during a dive in Mexico, and his reg immediately failed. He got air from a buddy, and later found that his reg was clogged with the same kind of powder from the rental cylinder.

I do not recall him saying that there was an audible rattle in his case. I think a better test would be inverting the tank and cracking the valve.

 

[Scared Silly]

The thingy is called a dip tube and the white powder is aluminum oxide. Sounds like a cylinder got a wee bit of water in it and there was corrosion. I have seen the same with rental LP72, except it was rust and still pretty liquid. That cylinder was toast.

If one hears rattling around inside a cylinder, as said it is more than likely the dip tube. Reject using the cylinder.

 

[halocline]

Another example of how regulators are NOT 'life support.' Someone could buy the most expensive regulator on the planet, have it serviced religiously by the best service tech on the planet, and still end up with no air on a dive due to something as simple as a bit of junk in the tank, and it does not take much to clog a filter or valve. In this case, like thousands of others, the buddy system works!

I've never had a regulator completely clog on me, but I have rebuilt a few with pretty nasty filters.

 

[Nemrod]

If the dip tube is missing or broken off (or unscrewed) and if there is FOD in the tank (oxidation, rust, bugs, marbles, left over tumbling agent) then yes, that failure can happen. The surface area of the flat type sintered filters is not very large, thus many regulators now use the conical type to increase surface area to prevent or reduce the possibility of filter clogging from a single event. Everything has it's limits.

N

 

[axxel57]

You need a very significant amount of Aluminum oxide (not Aluminum hydroxide), a missing dip tube, and a diver who dives head down steep to be able to clog your filter in a way, it is shutting off air supply.

Diving with rental gear of Diving Ventures I don't know, I usually use a white piece of cotton which I put around the tank valve, then opening the valve.

It's sometimes interesting what you find after that procedure on the cotton (moisture, aluoxide, rust etc). Also opening a bit the tank and smelling the air that comes from the tank can be helpful to identify problematic cylinders.

A completely blocked filter I have seen only once in the years I'm servicing regulators. An instructor brought me his reg, which I had serviced only two months earlier, telling me that he had to abort a dive with customers because of the 'failure' of his regulator.

One look on the filter made clear what the problem was.

 

[gert7to3]

Dare I say it? Get and use a pony bottle.